docs: def _get_solarflux(self):
          """Derive the in-band solar flux from rsr over the Near IR band (3.7
          or 3.9 microns)
          """
          solar_spectrum = \
              SolarIrradianceSpectrum(TOTAL_IRRADIANCE_SPECTRUM_2000ASTM,
                                      dlambda=0.0005,
                                      wavespace=self.wavespace)
          self.solar_flux = solar_spectrum.inband_solarflux(self.rsr[self.bandname])